Tar is released naturally from the seafloor of the Santa Barbara Channel, which is why a beach walk in the area often means tar on your feet.

Figure App.E.11.7.. A figure showing the deposition of tar (green) at Fraser Cove, Santa Cruz Island, compared to bare rock (red) and barnacle cover (grey) from 1994 - 2014.

Click for Details

Tar deposition percent cover (green) at Fraser Cove, Santa Cruz Island is compared to bare rock (red) and a barnacle complex (Balanus/Chtamalus, grey). The park only monitors tar at Fraser Cove and it is believed that tar at this location is from natural seeps. There was a slight decline (< 10 percent) in tar cover in 2014 from long-term mean, but tar still covered approximately 50 percent of plots. Figure: Channel Islands National Park

Figure App.E.11.8.. A figure showing tar deposition at Fraser Cove, Santa Cruz Island from 1994 - 2014.

Click for Details

Tar deposition percent cover at Fraser Cove, Santa Cruz Island. The park only monitors tar at Fraser Cove and it is believed that tar at this location is from natural seeps. The blue line represents the mean percent cover at a given year while the red dashed line represents the long-term mean. There was a slight decline (< 10 percent) in tar cover in 2014 from the long-term mean, but tar still covered approximately 50 percent of plots. Figure: Channel Islands National Park